Even if http proxy is configured on satellite v 6, while enabling Red Hat repository it fails with "No route to host - connect(2)"

Issue

• After completing Red Hat Satellite v 6 installation, with command katello-installer --katello-proxy-url=http://proxy.example.com --katello-proxy-port=8080. While exploring Red Hat repositories it fails:

Content -> Red Hat Repositories -> Enable Red Hat Repositories

There was an error attempting to retrieve the repository list:
No route to host - connect(2)